Serum Myostatin in Liver Cirrhosis: a Marker beyond Malnutrition

INTRODUCTION

In chronic liver disease, sarcopenia defined as: loss of muscle mass and/or muscle power, is a common finding that is related to complications and mortality in cirrhotic patients [1]. Patients with malnutrition undergoing liver transplantation are more susceptible to infections, and longer ICU stay with a higher mortality [2].

The etiology of malnutrition in patients with liver cirrhosis is multifactorial including decreased dietary intake due to anorexia, nausea, and vomiting. Additionally, intolerance to food with a high-fat content as there is decreased bile salt production in cirrhosis. Additionally, small intestinal mucous membrane edema because of hypoalbuminemia leads to decreased nutrient absorption. All these factors result in a reduction in glucose stores that leads to depletion of muscle mass and a dependency on protein stores for energy [3].

Sarcopenia occurs as a result of an imbalance between protein synthesis and protein breakdown in the skeletal muscles. In liver cirrhosis protein imbalance occurs due to several mechanisms including chronic inflammation, hyperammonemia, and endocrine abnormalities among others [4].

The subjective global assessment (SGA) is a nutrition assessment tool that refers to an overall evaluation of a patient's history and physical examination and uses structured clinical parameters to diagnose malnutrition [5]. Underweight cirrhotic patients (BMI < 14 kg/m2) have a higher risk of mortality and should be admitted to the hospital for the initiation of intensive nutritional support [6].

Myostatin, a myokine, plays a crucial role in muscle mass homeostasis. Myostatin is mainly produced by the skeletal muscles and is a strong negative regulator of muscle mass [7]. High levels of serum myostatin induce muscle wasting [8]. There is growing evidence on the impact of muscle wasting on the prognosis of liver disease, therefore myostatin has been a common research subject of different recent studies [9,10].

Based on the Child-Pugh scoring, the rate of sarcopenia increases as the severity of liver disease increases [11]. Also, liver cirrhosis is associated with increased serum myostatin levels, furthermore, high myostatin levels have been correlated with increased mortality rates among cirrhotic patients [12]. In patients undergoing evaluation for liver transplantation, a high serum myostatin was observed in comparison with controls [13] with a higher mortality over a 7-year follow-up [14].

Child-Pugh and model for end-stage liver disease (MELD) scores are non-invasive methods that are used in predicting the prognosis of liver cirrhosis, other indicators are still needed. Ideal serum biomarkers are needed to predict the prognosis of cirrhosis. Many efforts have been made to explore the prognostic value of various serum biomarkers at different stages of liver cirrhosis. Serum myostatin is a promising biomarker, that has a high value in patients with liver cirrhosis than in controls [15].

This study aimed to demonstrate the relationship between Myostatin and the degree of malnutrition and to show its role in prognosis in comparison to the model for end-stage liver diseases (MELD) score.

METHODOLOGY

The study was an observational, cross-sectional study carried out on 90 individuals attending the Tropical Medicine Department, at Alexandria Main University Hospital.

Group I: 70 patients with liver cirrhosis that were assessed by the subjective global assessment (SGA) and subdivided according to the presence or absence of malnutrition according to SGA.

Group II: 20 healthy controls.

Ethical approval was obtained, and informed consent was taken from each patient included in the study.

Exclusion criteria:

1. Female sex.
2. Heart failure.
3. Renal impairment.
4. Chronic obstructive pulmonary disease (COPD).
5. Diabetes mellitus.
6. Obesity (BMI more than 30).
7. Alcoholic hepatitis, Non-alcoholic steatohepatitis (by normal liver enzymes and ultrasound assessment).
8. Hepatocellular carcinoma (by normal alpha-fetoprotein and ultrasound assessment).

Malnutrition was assessed by:

1. Subjective global assessment (SGA): groups were divided into well-nourished and malnourished according to the SGA score. SGA was obtained by filling subjective global assessment form.[16]
2. Anthropometric measurements such as; muscle mass, Body mass index (BMI), and biochemical variables, were taken afterward for each group (well-nourished and malnourished).
3. Muscle mass measurements: Dry mass index:( [weight – TBW]/height2) [17], triceps Fold (TFT) [18], and mid-arm-muscle- circumference (MAMC).[19] (TBW: total body water: 2.447 – (0.09145 x age) + (0.1074 x height in centimeters) + (0.3362 x weight in kilograms) = total body water (TBW) in liters).
4. Muscle depletion was diagnosed according to standard values for the general population matched for age and sex as previously reported:
5. Controlling nutritional status (CONUT) score: it was calculated using serum albumin, total cholesterol concentrations, and total lymphocytic count. [20]

MELD and Child-Pugh scoring systems were calculated.

Assessment of serum myostatin was done by ELISA; Kit (E-EL-H1437) [21]

RESULTS

Routine Laboratory investigations and demographic data

As regards to subject's age, in the control group, it ranged between 25-31 years with a mean of 27.80 ± 2.15 years while in the cirrhosis group, it ranged between 42-78 years with a mean of 56.87 ±7.50 years. Statistically significant differences were found between the two groups.

A significant difference was found between cirrhotic patients and controls regarding serum platelets. (p = 0.005)

Serum alanine aminotransferase (ALT), total bilirubin, albumin, and international normalized ratio (INR), all were significantly different between cirrhotic patients and controls. (p value= 0.005, <0.001,

No significant difference was found between cirrhosis and controls regarding renal functions. 

      Table 1: Routine Laboratory investigations and demographic data

U: Mann Whitney                                              t: Student t-test                                     p: p-value for comparing between the two groups WBC: white blood cells                 LT: alanine aminotransferase              AST: aspartate aminotransferase

INR: international normalized ratio                  BUN: blood urea nitrogen

 Nutritional assessment

 Body mass index

Triceps fold measurements and controlling nutritional status (CONUT) score

For triceps fold measurements there was a significant reduction in a malnourished group rather than well-nourished patients (p=0.001) regarding the controlling nutritional status (CONUT) score, a significant increase in its values in malnourished patients was noticed. (p= 0.001).

Table (2):   Comparison between the two studied groups according to triceps fold (cm) and CONUT score

U: Mann Whitney test                                         CONUT score: controlling nutritional status score

p: p-value for comparing between the two groups.

 MELD and Child-Pugh scoring systems correlation to malnutrition

Malnutrition was observed in patients with Child grades B and C with a mean of 8.04 ± 2.23 (p = 0.002),

also, malnutrition was associated significantly with a higher MELD score with a mean of 13.43 ± 5.25 (p= 0.001)

Table (3): Comparison between the two studied groups according to different parameters

c²:  Chi-square                              U: Mann Whitney test                      MELD score: a model for end-stage liver disease

 SGA correlation to MELD and Child-Pugh scoring systems

A positive significant correlation was found between the degree of malnutrition (SGA) with both MELD score (p < 0.001) and child score (p=0.019).

SGA: subjective global assessment                                                                            MELD score: model for end-stage liver disease

F: F for ANOVA test, pairwise comparison between each 2 groups was done using a Post Hoc Test (Tukey)

H: H for Kruskal Wallis test, pairwise comparison bet. each 2 groups were done using Post Hoc Test (Dunn's for multiple comparisons test)

p: p-value for comparing between the three groups                                       p₁: p-value for comparing between Mild and Moderate

p₂: p-value for comparing between Mild and High                                        p₃: p-value for comparing between Moderate and High  

*: Statistically significant at p ≤ 0.05

 A positive significant correlation was found between the degree of malnutrition and the presence of hepatic encephalopathy. (p=0.001)

c²:  Chi-square test             MC: Monte Carlo     SGA: a subjective global assessment

p: p-value for comparing between the two groups.

Serum myostatin

Higher Serum myostatin was found in the malnourished group (median: 10.7 ng/ml) rather than in the well-nourished group (median:4.2 ng/ml) which is of significant difference (p=<0.001) 

Table (6): comparison of serum Myostatin between malnourished and well-nourished

     U: Mann Whitney test p: p value for comparing between the two groups.

moderate degree of malnutrition (median: 10.3 ng/ml) and mild degree of malnutrition (median: 7.4 ng/ml)

Table (7): Relation between degrees of malnutrition (SGA) with Serum myostatin

H: H for Kruskal Wallis test, pairwise comparison between each 2 groups were done using Post Hoc Test (Dunn's for multiple comparisons test)

p: p-value for comparing between the three groups                   p₁: p-value for comparing between Mild and Moderate

p₂: p-value for comparing between Mild and High                    p₃: p-value for comparing between Moderate and High               

*: Statistically significant at p ≤ 0.05

specificity of 84%, positive predictive value of 94.3 % and negative predictive value of 94.1%. Test accuracy was 94.3%.

 Table (8): Agreement (sensitivity, specificity) for serum myostatin to diagnose mall nourished from well-nourished